Process for Fabricating PBI Hollow Fiber Asymmetric Membranes for Gas Separation and Liquid Separation
AssigneeSRI International
InventorsIndira Jayaweera, Gopala N. Krishnan, Angel Sanjurjo, Palitha Jayaweera, Srinivas Bhamidi
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Abstract
The invention provides methods for preparing an asymmetric hollow fiber, the asymmetric hollow fibers prepared by such methods, and uses of the asymmetric hollow fibers. One method involves passing a polymeric solution through an outer annular orifice of a tube-in-orifice spinneret, passing a bore fluid though an inner tube of the spinneret, dropping the polymeric solution and bore fluid through an atmosphere over a dropping distance, and quenching the polymeric solution and bore fluid in a bath to form an asymmetric hollow fiber.
Claims15
A method for preparing an asymmetric hollow fiber, the method comprising:
- (a) passing, through an outer annular orifice of a tube-in-orifice spinneret, a polymeric solution comprising:
- (i) 15-25 wt % of a polybenzimidazole;
- (ii) 1-5 wt % of a polymeric pore-forming material;
- and (iii) a solvent with respect to the polybenzimidazole;
- (b) passing, though an inner tube of the spinneret, a bore fluid comprising:
- (i) 65-99 wt. % of a non-solvent with respect to the polybenzimidazole;
- and (ii) 1-35 wt. % of a solvent with respect to the polybenzimidazole, wherein the bore fluid maintains the polymeric solution in an annular shape;
- (c) dropping the polymeric solution and bore fluid through a gap, wherein the gap comprises an atmosphere and a dropping distance of 0.3 to 20 cm;
- (d) quenching the polymeric solution and bore fluid in a bath to form an asymmetric hollow fiber having an annular shape and comprising first and second concentric layers, wherein the first layer contacts the second layer and is non-porous, and wherein the second layer is porous having pores in the range 5-250 nm.
An asymmetric hollow fiber comprising first and second concentric layers forming a wall of the fiber, wherein:
- the asymmetric hollow fiber comprises a polybenzimidazole material;
- the first layer is non-porous and the second layer is porous having pores in the range 5-250 nm;
- and
- the asymmetric hollow fiber has an outside diameter in the range 100-2000 μm.
Dependencies are inferred from the claim text.